Adapting detection sensitivity based on evidence of irregular sinus arrhythmia to improve atrial fibrillation detection in insertable cardiac monitors

Figure 1. The schematic for the combination of the adaptive evidence with P-wave evidence and the Lorenz plot based AF detection algorithm. The three components of the algorithm, the Lorenz plot based AF evidence score, the P-wave evidence score, and the adaptive evidence score, is combined to generate a modified AF evidence score which is compared with threshold to detect AF. AF, atrial fibrillation.

Figure 2. An example to show how different steps of the Adaptive P-Sense algorithm reduces inappropriate AF episode detection in a patient with runs of ectopy and sinus arrhythmia. (A) The Lorenz plot based AF evidence score computed using only RR intervals. The score is greater than threshold for large proportion of time to generate false detections. (B) AF evidence score from Lorenz plot reduced by P-wave evidence score (P-Sense) show significant reduction of false detections. Segment A shows an example 2-min period inappropriately detected by Lorenz plot algorithm, but rejected by the P-Sense algorithm. (C) Periods of effective P-Sense algorithm leads to accumulation of adaptive evidence. The period shown in segment A increments the adaptive evidence score. (D) AF evidence score from Lorenz plot reduced by P-wave evidence and adaptive evidence illustrates how adaptive P-Sense further reduces false detection with the modified AF evidence score below threshold for entire 10-h duration. Segment-B shows a 2-min period where P-Sense is ineffective in rejecting false detection due to presence of baseline noise and faster rates, but Adaptive P-Sense is successful in rejecting the inappropriate…

Figure 3. Number of true AF episodes that are detected and number of falsely detected AF episodes before and after application of adaptive P-Sense algorithm. Significant reduction of false detections was achieved in development and both validation sets with minimal reduction in true detections. AF, atrial fibrillation.